USPTO Patents Application 09866600

TITLE OF THE INVENTION
STAGE APPARATUS WHICH SUPPORTS INTERFEROMETER, STAGE

POSITION MEASUREMENT METHOD, PROJECTION EXPOSURE
APPARATUS, PROJECTION EXPOSURE APPARATUS MAINTENANCE
5 METHOD, SEMICONDUCTOR DEVICE MANUFACTURING METHOD, AND

SEMICONDUCTOR MANUFACTURING FACTORY

FIELD OF THE INVENTION

The present invention relates to a stage apparatus

10 which supports an interferometer for measuring the
position of a stage movable in at least one axial
direction by using a laser interferometer and, more
particularly, to a stage apparatus which supports an
interferometer for measuring the position of a stage

15 having long and short stroke axes by using a laser

interferometer. Also, the present invention relates to a
projection exposure apparatus having this stage as a
reticle stage and/or wafer stage, and a method of
manufacturing a semiconductor device or the like by

20 using the projection exposure apparatus.

BACKGROUND OF THE INVENTION

Conventionally in the technical field which
requires high-precision processing, various processing
25 operations are done by setting an object to be processed
on a stage which can be aligned at high precision, and
controlling the stage. The prior art will be described

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r > > i

by exemplifying a projection exposure apparatus used in
the manufacture of a semiconductor device or the like.

In the projection exposure apparatus, a reticle
stage which supports a reticle or a wafer stage which
5 supports a wafer must be moved parallel to planes

perpendicular to each other along the X- and Y-axes in
exposure, and the stage position must be accurately
l«% measured and controlled. For this purpose, the

m projection exposure apparatus uses a laser

%^ 10 interferometer as a means for measuring the positions of

ji; X and Y strokes on the reticle or wafer stage in \x order

or less.

hf In general, the reticle or wafer stage slightly

W rotates within the X- and Y-axis planes ( 0 -axis

.-.atss.

O 15 direction) (yawing error) . The yawing error generated in

the reticle or wafer stage also slightly rotates a
reticle or wafer set on the stage along the 0 -axis, and
an error at the periphery cannot be ignored. Therefore,
this yawing error must be corrected. For example, a

20 laser interferometer obtains the X-direction positions
of two points on the reticle or wafer stage, and a
6 -axis displacement is measured from the difference
between the positions of the two points and the beam
span of the laser interferometer. In this manner, on the

25 reticle or wafer stage,- the X-axis position of one point
and the Y-axis positions of two points on the stage are
generally measured by using the laser interferometer in

r

f

order to measure X-, Y-, and 0 -axis positions.

Fig. 5 is a view showing a measurement principle
using a laser interferometer. A bar mirror on an X-Y
stage 12 is irradiated with a laser beam from the Y-axis
5 direction, and measurement is done by using the

reflected beam. When either of X and Y strokes is longer,
for example, when the Y-axis stroke is longer, as shown
in Fig. 5, a bar mirror for measuring an X-axis position
fg inevitably becomes longer along the Y-axis. A long bar

10 mirror makes the apparatus bulky. In addition, a

cantilever structure generates deflection and vibrations
^ of the bar mirror itself.

To prevent this, a bar mirror is eliminated from
Iff an X-Y stage in the invention disclosed in Japanese

S i

O 15 Patent Laid-Open No. 5-217837. This X-Y stage will be
described with reference to Fig. 6.

In Fig. 6, an X-Y stage 12 comprises a rectangular
Y table 14 movable in the Y-axis direction along a pair
of rails 13 extending parallel to the Y-axis, and a
20 rectangular X table 16 movable in the X-axis direction
along a pair of rails 15 laid parallel to the X-axis on
the Y table 14. A wafer W is held on the X table 16.

A laser interferometer is generally constituted by
an optical unit which receives a laser beam from a light
25 source, splits it into reference and measurement beams,
ensures the optical path of the reference beam, and
causes the reference and measurement beams to interfere

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with each other, a bar mirror for reflecting the
measurement beam, a detector for detecting the
interference beam, and the like.

A laser head 8 for generating a laser beam,
5 benders for deflecting the optical path of the laser
beam, beam splitters located between the benders to
split the laser beam, optical units (interferometers) 9a,
9b, and 9c each for splitting the laser beam into
reference and measurement beams and ensuring the optical

10 path of the reference beam, and detectors 10a, 10b, and
10c each for detecting the reference and measurement
beams are arranged outside the X-Y stage 12. Bar mirrors
11a and lib for reflecting the measurement beams of
laser beams and returning them to the optical units

15 (interferometers) 9a, 9b, and 9c are fixed at the edges
of two sides which face the optical units
(interferometers) 9a, 9b, and 9c and are perpendicular
to each other, thus constituting a laser interferometer.
This laser interferometer measures the positions

20 of the X and Y tables 16 and 14 and the position of the
wafer W. A laser beam emitted by the laser head 8 is
deflected by the bender and split into two laser beams
by the beam splitter. One of the split laser beams is
guided to the optical unit (interferometer) 9a where the

25 laser beam is split into reference and measurement beams.
The reference beam is repetitively reflected within the
interferometer 9a and guided to the detector 10a. The

measurement beam emerges from the optical unit
(interferometer) 9a, reaches the bar mirror 11a held by
the X table 16, and is reflected to return to the
optical unit (interferometer) 9a. The measurement beam
5 reaches the bar mirror 11a again, is reflected, and
guided to the detector 10a via the optical unit
( interferometer) 9a .

The optical path until the reference beam is
incident on the detector 10a is constant regardless of

10 the position of the Y table 14. The optical path until
the measurement beam is incident on the detector 10a
depends on the Y-axis position of the bar mirror 11a on
the X table 16 that reflects the measurement beam, and
the measurement beam includes position information of

15 the Y table 14. These optical paths are compared to
measure a distance y between the optical unit
(interferometer) 9a along the Y-axis and the bar mirror
11a at a point A where the bar mirror 11a held by the X
table 16 reflects the measurement beam, and the position

20 of the Y table 14. The other laser beam split by the
beam splitter is split into two laser beams by another
beam splitter. One of the split laser beams is directly
guided to one of the optical units (interferometers) 9b
and 9c, whereas the other is deflected in optical path

25 by another bender and guided to the other optical unit

(interferometer) . Each of the laser beams guided to the
optical units (interferometers) 9b and 9c is split into

reference and measurement beams. The measurement beams
reciprocate twice between the optical units
(interferometers) 9b and 9c and the bar mirror lib, and
the reference beams are repetitively reflected within
5 the respective optical units (interferometers) 9b and 9c.
Then, the reference and measurement beams are guided to
the detectors 10b and 10c. Distances xl and x2 between
the optical units (interferometers) 9b and 9c and the
bar mirror lib along the X-axis at points B and C where
10 the bar mirror lib held by the X table 16 reflects the
laser beams, and the position of the X table 16
including the two points can be measured from the
reference and measurement beams guided to the detectors
10b and 10c.

15 The X-axis positions (distances) xl and x2 of two

points on the X table 16 and the Y-axis position
(distance) y of one point can provide the position of
the X-Y stage 12 and the X-, Y-, and Q -axis positions of
the wafer W. In Japanese Patent Laid-Open No. 5-217837,

20 the bar mirrors are ariranged on the sides of respective
tables in their movement directions on the X-Y stage for
measuring the positions of the tables by using the laser
interferometer and the bar mirrors for reflecting a
laser beam from the laser interferometer. At the same

25 time, the optical units (interferometers) of the laser
interferometer are held at side edges facing the bar
mirrors of the X table.

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In Japanese Patent Laid-Open No. 5-217837, the X-Y
stage can be downsized by arranging the bar mirrors
outside the stage movable portion. However, the
detectors are arranged on the stage movable portion, so
5 optical fibers must be laid out on the stage,
complicating the wiring of the moving stage.

SUMMARY OF THE INVENTION
The present invention has been made to overcome

10 the conventional drawbacks, and has as its object to

provide a movable stage apparatus which can be downsized
as a whole and realizes high-precision measurement by a
laser interferometer .

The present inventor has made extensive studies to

15 find that the above problem can be solved by mounting

the optical unit of at least one laser interferometer on
a stage movable portion.

More specifically, a stage apparatus according to
the present invention comprises a stage movable along at

20 least one axis, a laser head for generating a laser beam,
an optical unit which is mounted on the stage and splits
the laser beam into reference and measurement beams, a
mirror which is arranged outside the stage and reflects
the measurement beam, and a detector for detecting an

25 interference beam of the reference and measurement beams.
The optical unit can make the reference and measurement
beams interfere with each other. Alternatively, the

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detector can make the reference and measurement beams
interfere with each other.

In the stage apparatus of the present invention, a
direction of the laser beam and a direction of the
measurement beam from the optical unit that irradiates
the mirror are preferably perpendicular to each other.

In the stage apparatus of the present invention,
the stage is movable along X- and Y-axes. The stage can
be longer in movement stroke along the Y-axis than along
the X-axis. The direction of the laser beam can be
parallel to the Y-axis, and the measurement beam can be
parallel to the X-axis. The stage is movable along a
Z-axis. The stage apparatus can further comprise an
optical unit for emitting a measurement beam along the
Z-axis. The stage is movable along the Z-axis.

In the stage apparatus of the present invention, a
reflecting member for reflecting the measurement beam
emitted from the Y-axis direction can be mounted on the
stage. The measurement beam which irradiates the stage
from the Y-axis direction can include a plurality of
beams. A Z-axis position of the stage can be measured by
using the measurement beam which irradiates the stage
from the Y-axis direction. Further, an X-axis position
of the stage can be measured by using the measurement
beam which irradiates the stage from the Y-axis
direction.

In the stage apparatus of the present invention, a

plurality of optical units for irradiating the mirror
with the measurement beam can be mounted on the stage.
The Z-axis position of the stage can be measured by
using the measurement beam from the optical unit that
5 irradiates the mirror. The Y-axis position of the stage
can be measured by using the measurement beam from the
optical unit that irradiates' the mirror.

In the stage apparatus of the present invention, a
shape of the mirror arranged outside the stage can be

10 measured based on pieces of Y-axis position information
of at least two points on the stage, and pieces of
X-axis position information of at least two points on
the stage that are measured by using the plurality of
optical units. The X-axis position information on the

15 stage that is measured by using the optical unit can be
corrected based on a measurement result of the shape of
the mirror.

In the stage apparatus of the present invention,
positions of six axes of the stage can be measured by
20 using a laser beam. The mirror arranged outside the

stage is preferably supported at a Bessel point of the
mirror.

In the stage apparatus of the present invention, a
driving mechanism for driving the stage is controlled
25 based on a measurement result of a position of the stage.

In the stage apparatus of the present invention,
the stage can include a reticle stage which supports a

reticle .

A stage position measurement method according to
the present invention comprises the steps of generating
a laser beam from a laser head, irradiating an optical
5 unit mounted on a movable stage with the laser beam,

splitting the laser beam into reference and measurement
beams by the optical unit, irradiating a mirror arranged
outside the stage with the measurement beam, reflecting
the measurement beam which irradiates the mirror, making

10 the reflected measurement beam interfere with the

reference beam, detecting an interference beam, and
measuring a position of the stage on the basis of a
signal concerning the detected interference beam.

A projection exposure apparatus according to the

15 present invention can comprise the stage apparatus as a
reticle stage and/or a wafer stage.

A semiconductor device manufacturing method
according to the present invention comprises the steps
of installing manufacturing apparatuses for various

20 processes including the projection exposure apparatus in
a semiconductor manufacturing factory, and manufacturing
a semiconductor device by using the manufacturing
apparatuses in a plurality of processes. The method can
further comprise the steps of connecting the

25 manufacturing apparatuses by a local area network, and
communicating information about at least one of the
manufacturing apparatuses between the local area network

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and an external network outside the semiconductor
manufacturing factory. A database provided by a vendor
or user of the projection exposure apparatus can be
accessed via the external network to obtain maintenance
information of the manufacturing apparatus by data
communication, or production management can be performed
by data communication between the semiconductor
manufacturing factory and another semiconductor
manufacturing factory via the external network.

A semiconductor manufacturing factory according to
the present invention comprises manufacturing
apparatuses for various processes including the
projection exposure apparatus, a local area network for
connecting the manufacturing apparatuses, and a gateway
which allows the local area network to access an
external network outside the factory, wherein
information about at least one of the manufacturing
apparatuses can be communicated.

A maintenance method for the projection exposure
apparatus installed in a semiconductor manufacturing
factory comprises the steps of causing a vendor or user
of the exposure apparatus to provide a maintenance
database connected to an external network of the
semiconductor manufacturing factory, authorizing access
from the semiconductor manufacturing factory to the
maintenance database via the external network, and
transmitting maintenance information accumulated in the

maintenance database to the semiconductor manufacturing
factory via the external network.

Other objects and advantages besides those
discussed above shall be apparent to those skilled in
the art from the description of a preferred embodiment
of the invention which follows. In the description,
reference is made to accompanying drawings, which form
apart thereof, and which illustrate an example of the
invention. Such example, however, is not exhaustive of
the various embodiments of the invention, and therefore
reference is made to the claims which follow the
description for determining the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a view showing a stage apparatus
according to the first embodiment of the present
invention;

Fig. 2 is a view showing a stage apparatus
according to the second embodiment of the present
inventions-
Figs. 3A and 3B are views showing a stage
apparatus according to the third embodiment of the
present invention;

Fig. 4 is a sectional view showing an exposure
apparatus having a stage apparatus according to the
fourth embodiment of the present invention;

Fig. 5 is a view showing the measurement principle

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of a conventional stage apparatus;

Fig. 6 is a view showing the conventional stage
apparatus;

Fig. 7 is a view showing the concept of a
semiconductor device production system when viewed from
a given angle;

Fig. 8 is a view showing the concept of the
semiconductor device production system when viewed from
another given angle;

Fig. 9 is a view showing an example of a user
interfaces-
Fig. 10 is a flow chart showing a device
manufacturing process; and

Fig. 11 is a flow chart for explaining a wafer
process .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of a stage apparatus which
supports an interferometer according to the present
invention will be described with reference to Figs. 1 to
3.

(First Embodiment)

Fig. 1 shows a stage apparatus which is a triaxial
stage having X-, Y-, and 6 -axes with a degree of freedom
25 in the plane direction. In this stage apparatus, the
stroke is long along the Y-axis , and short along the
6 -axis and the X-axis perpendicular to the Y-axis. The

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bar mirror of a laser interferometer for measuring the
long-stroke axis (Y-axis) is mounted on a stage movable
portion, and its optical unit and detector are arranged
outside the stage movable portion. The optical unit of a
laser interferometer for measuring the short-stroke axes
(X- and 0-axis) is mounted on a stage movable portion,
and its bar mirror and detector are arranged outside the
stage movable portion.

In Fig. 1, a reticle stage 1 is supported on a
guide 2 in a non-contact manner by a hydrostatic bearing
(not shown) so as to be movable along the three, X-, Y-,
and 0-axes. The reticle stage 1 supports a reticle (not
shown) , and is driven by linear motors 3 serving as a
driving mechanism with a long stroke along the Y-axis
and a short stroke along the X- and 0-axes. The linear
motors 3 are arranged on the two sides of the reticle
stage 1.

Each linear motor 3 has movable and stationary
elements 4 and 5 integrated into the reticle stage 1.
The movable element 4 has a Y magnet (not shown) and X
magnet. The stationary element 5 has a plurality of Y
coils 6 aligned along the Y-axis, and an X coil 7 as a
single-phase coil. The Y magnet faces the Y coils 6. A
current flowing through a selected Y coil 6 allows the
movable element 4 to obtain a driving force in the Y
direction. If the two linear motors apply a driving
force in a direction opposite to the Y direction, the

reticle stage 1 can obtain a driving force in the 9 -axis
direction. The X magnetic faces the X coil 7. A current
flowing through the X coil 7 allows the movable element
to obtain a driving force in the X direction.

A laser interferometer is generally constituted by
an optical unit which receives a laser beam from a light
source, splits it into reference and measurement beams,
ensures the optical path of the reference beam, and
cause the reference and measurement beams to interfere
with each other, a bar mirror for reflecting the
measurement beam, a detector for detecting the
interference beam, and the like.

Laser heads 8a and 8b each for generating a laser
beam, optical units (interferometers) 9a and 9b each for
splitting the laser beam into reference and measurement
beams and ensuring the optical path of the reference
beam, and detectors 10a and 10b each for detecting the
reference and measurement beams are arranged outside the
reticle stage 1. Bar mirrors 11a and lib for reflecting
the measurement beams of laser beams and returning them
to the optical units (interferometers) 9a and 9b are
fixed at one side edge which faces the optical units
(interferometers) 9a and 9b of the reticle stage 1, thus
constituting a Y-axis laser interferometer. Note that
the members (11a and lib) for reflecting the measurement
beams are not limited to the bar mirrors and may be
corner cubes. The bar mirrors 11a and lib are long

enough for the measurement beams not to fall outside
them even if the reticle stage 1 moves with a short
stroke along the X-axis.

Laser heads 8c and 8d each for generating a laser
beam, and detectors 10c and lOd each for detecting
reference and measurement beams are arranged outside the
reticle stage 1. Optical units (interferometers) 9c and
9d each for splitting a laser beam into reference and
measurement beams and ensuring the optical path of the
reference beam are mounted on the reticle stage 1. The
reticle stage 1 moves with a short stroke along the
X-axis. Even if the reticle stage 1 moves along the
X-axis , laser beams from the laser heads 8c and 8d do
not fall outside the optical units (interferometers)
mounted on the reticle stage 1.

A long bar mirror 11c which extends along the
Y-axis, faces the optical units (interferometers) 9c and
9d, and reflects the measurement beam of a laser beam to
return it to the optical units (interferometers) 9c and
9d is fixed outside the reticle stage 1, thereby
constituting an X-axis laser interferometer. The bar
mirror 11c is desirably supported at its Bessel point
because it is long along the Y-axis.

These Y-axis and X-axis laser interferometers
measure the position of the reticle stage 1 and that of
a set reticle (not shown) . More specifically, laser
beams emitted by the laser heads 8a, 8b, 8c, and 8d are

guided to the optical units (interferometers) 9a, 9b, 9c,

and 9d where each laser beam is split into reference and
measurement beams. The reference beams are repetitively

reflected within the interferometers 9a, 9b, 9c, and 9d
and guided to the detectors 10a, 10b, 10c, and lOd. The
measurement beams emerge from the optical units

(interferometers) 9a, 9b, 9c, and 9d, reach the bar
mirrors 11a and lib held by the reticle stage 1 and the
bar mirror 11c arranged outside the reticle stage 1, and
are reflected to return to the optical units

(interferometers) 9a, 9b, 9c, and 9d. The measurement
beams reach the bar mirrors 11a, lib, and 11c again, are
reflected, and guided to the detectors 10a, 10b, 10c,
and lOd via the optical units (interferometers) 9a, 9b,
9c, and 9d.

The optical paths until the reference beams are
incident on the detectors 10a and 10b are constant
regardless of the position of the reticle stage. The
optical paths "until the measurement beams are incident
on the detectors 10a and 10b depend on the Y-axis
positions of the bar mirrors 11a and lib on the reticle
stage 1 that reflect the measurement beams, and the
measurement beams contain position information of the
reticle stage 1. These optical paths are compared to
measure distances y between the optical units
(interferometers) 9a and 9b along the Y-axis and the bar
mirrors 11a and lib at points A and B where the bar

mirrors 11a and lib held by the reticle stage 1 reflect
the measurement beams, and the position of the reticle
stage 1.

Laser beams from the laser heads 8c and 8d are
respectively guided to the optical units
(interferometers) 9c and 9d. Each of the laser beams
guided to the optical units (interferometers) 9c and 9d
is split into reference and measurement beams. The
measurement beams reciprocate twice between the optical
units (interferometers) 9c and 9d and the bar mirror 11c,
and the reference beams are repetitively reflected
within the respective optical units (interferometers) 9c
and 9d. Then, the reference and measurement beams are
guided to the detectors 10c and lOd. Distances xl and x2
between the optical units (interferometers) 9c and 9d
and the bar mirror 11c along the X-axis at points C and
D where the bar mirror 11c reflects the laser beams, and
the position of the reticle stage 1 including the two
points can be measured from the reference and
measurement beams guided to the detectors 10c and lOd.

In the above description, the optical units 9c and
9d mounted on the reticle stage 1 are interferometers
where reference and measurement beams interfere with
each other, and the interference beams irradiate the
detectors 10c and lOd. However, the first embodiment
suffices to split a laser beam into reference and
measurement beams on the reticle stage 1, and need not

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always make the reference and measurement beams
interfere with each other on the reticle stage 1. For
example, the optical units mounted on the reticle stage
1 may only multiplex reference and measurement beams
without making them interfere with each other, and the
detectors 10c and lOd arranged outside the reticle stage
1 may make the reference and measurement beams interfere
with each other.

The X-axis positions (distances) xl and x2 of two
points on the reticle stage 1 and the Y-axis positions
(distances) yl and y2 of two points can provide the
position of the reticle stage 1 and the X-, Y-, and
6 -axis positions of the reticle.

The X-axis position of the reticle stage 1 is
obtained from xl and x2, but their average may be used
as the X-axis position of the reticle stage 1. Similarly,
the Y-axis position of the reticle stage 1 is obtained
from yl and y2, but their average may be used as the
Y-axis position of the reticle stage 1. The 9 -axis
position of the reticle stage 1 is obtained from the
positions xl and x2 and the beam span, but is also be
obtained from the positions yl and y2 and the beam span.
Thus, 9 -direction position information measured by the
two methods may be averaged.

In Fig. 1, the X- and Y-axis directions are
respectively measured by the two optical units
(interferometers) 9a and 9b and the two optical units

(interferometers) 9c and 9d, but both or one of the
X- and Y-axis directions can also be measured by one
optical unit. If the interferometer using one of the
optical units (interferometers) 9c and 9d is eliminated
from the arrangement of Fig. 1, the position of the
reticle stage 1 along the three axes (X-, Y-, and
0-axes) can be measured.

The 0 -direction position of the reticle stage can
be calculated from the Y-axis positions yl and y2 of two
points on the reticle stage 1 and their spans, and the
shape of the bar mirror 11c can be measured based on the
calculated value and the positions xl and x2 . For this
reason, the shape of the bar mirror 11c may be measured
in advance to correct the measurement results of xl and
x2 serving as pieces of X-axis position information of
two points on the reticle stage 1 on the basis of the
measurement result .

To measure the X-axis position of the reticle
stage by using the bar mirror 11c, the optical units
(interferometers) 9c and 9d each for splitting a laser
beam into reference and measurement beams and ensuring
the optical path of the reference beam may not be
mounted on the reticle stage 1 but may be arranged
outside the stage. In this case, the reticle stage 1 is
eguipped with an optical element for irradiating the bar
mirror 11c with a measurement beam from the optical unit
(interferometer) that is incident from the Y-axis

direction, and returning a measurement beam from the
X-axis direction that is reflected by the bar mirror 11c
to the optical unit (interferometer) . In this
arrangement, however, the optical path of the
measurement beam is long, and a fluctuation in the
atmosphere around the optical path caused by a
temperature change generates a large measurement error.
That is, the measurement result is readily influenced by
the fluctuation because the optical path until the
reference beam is incident on the detector is constant,
but the measurement beam split by the optical unit
(interferometer) arranged outside the reticle stage 1
reaches the optical element mounted on the reticle stage
via a long-stroke optical path along the Y-axis, is
reflected by the bar mirror 11c to return to the optical
element again, and reaches the optical unit via the
long-stroke optical path along the Y-axis.

To the contrary, in the embodiment of Fig. 1, the
optical units (interferometers) are mounted on the stage.
Even if the atmosphere fluctuates between the laser
heads 8c and 8d and the optical units (interferometers)
9c and 9d, the measurement result is hardly influenced.
This is because an optical path common to reference and
measurement beams is formed between the laser heads 8c
and 8d and the optical units (interferometers) 9c and 9d
(in other words, the optical path of the interference
beam of the reference and measurement beams is formed

between the laser heads 8c and 8d and the optical units
(interferometers) 9c and 9d) .

When, therefore, the X-axis position of the
reticle stage 1 is measured by using the bar mirror 11c
arranged outside the reticle stage, the measurement
precision is higher in the arrangement in which the
optical units (interferometers) are mounted on the
reticle stage, as shown in Fig. 1, than in the
arrangement in which they are arranged outside the
reticle stage.

According to the first embodiment, the position of
the reticle stage can be measured at high precision, and
the stage can be aligned at high precision by
controlling based on this measurement result the linear
motors for driving the stage.

According to the first embodiment, the position of
the reticle stage can be reliably measured without
holding by the reticle stage the bar mirror which
becomes longer in proportion to the stroke. This can
minimize the size of the reticle stage regardless of the
size of the bar mirror. Since the detectors are arranged
outside the stage, no optical cable or the like need be
laid out on the stage, and the whole reticle stage can
be reduced in size and weight.
(Second Embodiment)

Fig. 2 shows an interferometer-mounted stage
according to the second embodiment.

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In the first embodiment, the stage 1 has a
one-plate structure, is supported on the guide 2 in
three axial directions, and is movable in the three
axial directions. In the second embodiment, a stage has
a stacked structure, and is mounted on a Y stage which
moves with a long stroke along the Y-axis. The stage is
movable with a short stroke in the X and 6 directions on
the Y stage. That is, the stage is movable in the three
axial directions including Y-axis movement of the Y
stage .

Fig. 2 shows an interferometer-mounted stage which
is a triaxial stage having X-, Y-, and 0 -axes with a
degree of freedom in the plane direction. In this stage,
the stroke is long along the Y-axis, and short along the
0 -axis and the X-axis perpendicular to the Y-axis. The
bar mirror of a laser interferometer for measuring the
long-stroke axis (Y-axis) is mounted on a stage movable
portion, and its optical unit and detector are arranged
outside the stage movable portion. The optical unit of a
laser interferometer for measuring the short-stroke axes
(X- and 0-axis) is mounted on a stage movable portion,
and its bar mirror and detector are arranged outside the
stage movable portion.

In Fig. 2, an X-Y stage 12 comprises a rectangular
Y table 14 movable in the Y-axis direction along a pair
of rails 13 extending parallel to the Y-axis, and a
rectangular X table 16 movable in the X-axis direction

along a pair of rails 15 laid parallel to the X-axis on
the Y table 14. A substrate is held on the X table 16.

A laser interferometer is generally constituted by
an optical unit which receives a laser beam from a light
source, splits it into reference and measurement beams,
ensures the optical path of the reference beam, and
causes the reference and measurement beams to interfere
with each other, a bar mirror for reflecting the
measurement beam, a detector for detecting the
interference beam, and the like.

Laser heads 8a and 8b each for generating a laser
beam, optical units (interferometers) 9a and 9b each for
splitting the laser beam into reference and measurement
beams and ensuring the optical path of the reference
beam, and detectors 10a and 10b each for detecting the
reference and measurement beams are arranged outside the
X-Y stage 12. Bar mirrors 11a and lib for reflecting the
measurement beams of laser beams and returning them to
the optical units (interferometers) 9a and 9b are fixed
at one side edge which faces the optical units
(interferometers) 9a and 9b of the X table 16 which
moves along the Y-axis on the Y table 14, thus
constituting a Y-axis laser interferometer. Note that
the members (11a and lib) for reflecting the measurement
beams are not limited to the bar mirrors and may be
corner cubes. The bar mirrors 11a and lib are long
enough for the measurement beams not to fall outside

them even if the X table 16 moves with a short stroke
along the X-axis.

Laser heads 8c and 8d each for generating a laser
beam, and detectors 10c and lOd each for detecting
reference and measurement beams are arranged outside the
X-Y stage 12. Optical units (interferometers) 9c and 9d
each for splitting a laser beam into reference and
measurement beams and ensuring the optical path of the
reference beam are mounted on the X-Y stage 12. The X
table 16 moves with a short stroke along the X-axis.
Even if the X table 16 moves along the X-axis, laser
beams from the laser heads 8c and 8d do not fall outside
the optical units (interferometers) mounted on the X
table 16.

A long bar mirror 11c which extends along the
Y-axis, faces the optical units (interferometers) 9c and
9d on the X table 16, and reflects the measurement beam
of a laser beam to return it to the optical units
(interferometers) 9c and 9d is fixed outside the Y table
14, thereby constituting an X-axis laser interferometer.
The bar mirror 11c is desirably supported at its Bessel
point because it is long along the Y-axis,

These Y-axis and X-axis laser interferometers
measure the positions of the X and Y tables 16 and 14
and that of the substrate. More specifically, laser
beams emitted by the laser heads 8a, 8b, 8c, and 8d are
guided to the optical units (interferometers) 9a, 9b, 9c,

and 9d where each laser beam is split into reference and
measurement beams. The reference beams are repetitively
reflected within the interferometers 9a, 9b, 9c, and 9d
and guided to the detectors 10a, 10b, 10c, and lOd. The
measurement beams emerge from the optical units
(interferometers) 9a, 9b, 9c, and 9d, reach the bar
mirrors 11a and lib held by the X table 16 and the bar
mirror 11c arranged outside the Y table 14, and are
reflected to return to the optical units
(interferometers) 9a, 9b, 9c, and 9d. The measurement
beams reach the bar mirrors 11a, lib, and 11c again, are
reflected, and guided to the detectors 10a, 10b, 10c,
and lOd via the optical units (interferometers) 9a, 9b,
9c, and 9d.

The optical paths until the reference beams are
incident on the detectors 10a and 10b are constant
regardless of the position of the Y table 14. The
optical paths until the measurement beams are incident
on the detectors 10a and 10b depend on the Y-axis
positions of the bar mirrors 11a and lib on the X table
16 that reflect the measurement beams, and the
measurement beams contain position information of the Y
table 14. These optical paths are compared to measure
distances y between the optical units (interferometers)
9a and 9b along the Y-axis and the bar mirrors 11a and
lib at points A and B where the bar mirrors 11a and lib
held by the X table 16 reflect the measurement beams,

and the position of the Y table 14.

Laser beams from the laser heads 8c and 8d are
respectively guided to the optical units
(interferometers) 9c and 9d. Each of the laser beams
guided to the optical units (interferometers) 9c and 9d
is split into reference and measurement beams. The
measurement beams reciprocate twice between the optical
units (interferometers) 9c and 9d and the bar mirror 11c,
while the reference beams are repetitively reflected
within the respective optical units (interferometers) 9c
and 9d. Then, the reference and measurement beams are
guided to the detectors 10c and lOd. Distances xl and x2
between the optical units (interferometers) 9c and 9d
and the bar mirror 11c along the X-axis at points C and
D where the bar mirror 11c reflects the laser beams, and
the position of the X table 16 including the two points
can be measured from the reference and measurement beams
guided to the detectors 10c and lOd.

In the above description, the optical units 9c and
9d mounted on the X table 16 are interferometers where
reference and measurement beams interfere with each
other, and the interference beams irradiate the
detectors 10c and lOd. However, the second embodiment
suffices to split a laser beam into reference and
measurement beams on the X table 16, and need not always
make the reference and measurement beams interfere with
each other on the X table 16. For example, the optical

- 27 -

units mounted on the X table 16 may only multiplex
reference and measurement beams without making them
interfere with each other, and the detectors 10c and lOd
arranged outside the X table 16 may make the reference
and measurement beams interfere with each other.

The X-axis positions (distances) xl and x2 of two
points on the X table 16 and the Y-axis positions
(distances) yl and y2 of two points can provide the
position of the X-Y stage 12 and the X-, Y-, and 6 -axis
positions of the substrate.

The X-axis position of the X table 16 is obtained
from xl and x2, but their average may be used as the
X-axis position of the X table 16. Similarly, the Y-axis
position of the Y table 14 is obtained from yl and y2,
but their average may be used as the Y-axis position of
the Y table 14. The 6 -axis position of the X table 16
is obtained from the positions xl and x2 and the beam
span, but is also be obtained from the positions yl and
y2 and the beam span. Thus, 6 -direction position
information measured by the two methods may be averaged.

In Fig. 2, the X- and Y-axis directions are
respectively measured by the two optical units
(interferometers) 9a and 9b and the two optical units
(interferometers) 9c and 9d, but both or one of the
X- and Y-axis directions can also be measured by one
optical unit. If the interferometer using one of the
optical units (interferometers) 9c and 9d is eliminated

from the arrangement of Fig. 2, the position of the X-Y
stage 12 along the three axes (X-, Y-, and 6 -axes) can
be measured.

The 9 -direction position of the Y table 14 can be
calculated from the Y-axis positions yl and y2 of two
points on the Y table 14 and their spans, and the shape
of the bar mirror 11c can be measured based on the
calculated value and the positions xl and x2 . For this
reason, the shape of the bar mirror 11c may be measured
in advance to correct the measurement results of xl and
x2 serving as pieces of X-axis position information of
two points on the X table 16 on the basis of the
measurement result .

To measure the X-axis position of the X table 16
by using the bar mirror 11c, the optical units
(interferometers) 9c and 9d each for splitting a laser
beam into reference and measurement beams and ensuring
the optical path of the reference beam may not be
mounted on the X table 16 but may be arranged outside
the stage. In this case, the X table 16 is equipped with
an optical element for Irradiating the bar mirror 11c
with a measurement beam from the optical unit
(interferometer) that is incident from the Y-axis
direction, and returning a measurement beam from the
X-axis direction that is reflected by the bar mirror 11c
to the optical unit (interferometer) . In this
arrangement, however, the optical path of the

measurement beam is long, and a fluctuation in the
atmosphere around the optical path caused by a
temperature change generates a large measurement error.
That is, the measurement result is readily influenced by
the fluctuation because the optical path until the
reference beam is incident on the detector is constant,
but the measurement beam split by the optical unit
(interferometer) arranged outside the X table 16 reaches
the optical element mounted on the X table 16 via a
long-stroke optical path along the Y-axis, is reflected
by the bar mirror 11c to return to the optical element
again, and reaches the optical unit via the long-stroke
optical path along the Y-axis.

To the contrary, in the embodiment of Fig. 2, the
optical units (interferometers) are mounted on the X
table 16. Even if the atmosphere fluctuates between the
laser heads 8c and 8d and the optical units
(interferometers) 9c and 9d, the measurement result is
hardly influenced. This is because an optical path
common to reference and measurement beams is formed
between the laser heads 8c and 8d and the optical units
(interferometers) 9c and 9d (in other words, the optical
path of the interference beam of the reference and
measurement beams is formed between the laser heads 8c
and 8d and the optical units (interferometers) 9c and
9d) .

When, therefore, the X-axis position of the X

table 16 is measured by using the bar mirror 11c
arranged outside the X table 16, the measurement
precision is higher in the arrangement in which the
optical units (interferometers) are mounted on the X
5 table 16, as shown in Fig. 2, than in the arrangement in
which they are arranged outside the X table 16.

According to the second embodiment, the position
of the X-Y stage 12 can be measured at high precision,
and the stage can be aligned at high precision by

10 controlling based on this measurement result the linear
motors for driving the stage.

According to the second embodiment, the positions
of the X and Y tables can be reliably measured without
holding by the X-Y stage the bar mirror which becomes

15 longer in proportion to the stroke. This can minimize
the sizes of the X and Y tables regardless of the size
of the bar mirror. Since the detectors are arranged
outside the stage, no optical cable or the like need be
laid out on the stage, and the whole X-Y stage can be

20 reduced in size and weight. In the second embodiment,
the X table 16 is movable with a short stroke in the X
and 6 directions on the Y table 14. However, this
embodiment is not limited to this. For example, the X
table 16 may be movable with a short stroke in only the

25 X direction on the Y table 14, or may be movable with a
short stroke in the X, Y, and 6 directions.
(Third Embodiment)

- 31 -

Figs. 3A and 3B show an interferometer-mounted
stage having six degrees of freedom. In this stage, the
stroke is long along the Y-axis, and short along the
X- and Z-axes. The bar mirror of a laser interferometer
for measuring the long-stroke axis (Y-axis) is mounted
on a stage movable portion, and its optical unit and
detector are arranged outside the stage movable portion.
The optical unit of a laser interferometer for measuring
the short-stroke axes (X- and Z-axis) is mounted on a
stage movable portion, and its bar mirror and detector
are arranged outside the stage movable portion.

As shown in Fig. 3A, the long-stroke axis (Y-axis)
is measured by the bar mirror mounted on the stage
movable portion and the optical unit and detector
arranged outside the stage movable portion. Another
optical unit is mounted on the stage movable portion,
and the short-stroke axis (X-axis) is measured by the
bar mirror and detector arranged outside the stage
movable portion. This is similar to the first embodiment,
and a description thereof will be omitted.

In the third embodiment, an optical unit
(interferometer) 9e for splitting a laser beam into
reference and measurement beams and sending the
measurement beam along the Z-axis is disposed adjacent
to an optical unit (interferometer) 9c mounted on a
reticle stage 1. A bar mirror lid is arranged outside
the stage movable portion along the Z-axis of the

- 32 -

optical unit (interferometer) 9e. As shown in Fig. 3B, a
distance zl to a point E is measured by interference
with this bar mirror.

In the third embodiment,, an optical unit
5 (interferometer) 9f for splitting a laser beam into
reference and measurement beams and sending the
measurement beam along the X-axis is disposed adjacent
to the optical unit (interferometer) 9c mounted on the
reticle stage. The measurement beam from the optical

10 unit that irradiates a bar mirror 11c is formed at a
predetermined interval from the measurement beam from
the optical unit (interferometer) 9c in the Z direction.
X-axis position information of the reticle stage 1 and co
y (Y-axis position information) of the reticle stage 1

15 can be obtained on the basis of obtained information PX1,
X-axis position information XI obtained by using the
optical unit (interferometer) 9c, and the beam spans of
the two measurement beams in the Z direction. Note that
X-axis position information of the reticle stage 1 may

20 be obtained by averaging the pieces of position
information PX1 and XI.

In the third embodiment, an optical unit
(interferometer) for splitting a laser beam into
reference and measurement beams and sending the

25 measurement beam along the Y-axis is disposed adjacent
to an optical unit (interferometer) 9a arranged outside
the reticle stage. The measurement beam from the optical

- 33 -

unit that irradiates a bar mirror 11a is formed at a
predetermined interval from the measurement beam from
the optical unit (interferometer) 9a in the Z direction.
Y-axis position information of the reticle stage 1 and co
5 x (X-axis position information) of the reticle stage 1

can be obtained on the basis of obtained information PY1,
Y-axis position information Yl obtained by using the
optical unit (interferometer) 9a, and the beam spans of
the two measurement beams in the Z direction. Note that

10 Y-axis position information of the reticle stage 1 may
be obtained by averaging the pieces of position
information PYl and Yl .

The six degrees of freedom of the stage are
measured by data obtained from these interferometers.

1 5 ( Fourth Embodiment )

An embodiment of a scanning exposure apparatus on
which the interferometer-mounted stage apparatus of the
first embodiment is mounted as a reticle stage will be
explained with reference to Fig. 4.

20 A lens barrel surface plate 17 is supported by a

floor or base 18 via a damper 19. The lens barrel
surface plate 17 supports a reticle stage surface plate
20 and a projection optical system 23 which is
positioned between a reticle stage 21 and a wafer stage

25 22.

The wafer stage 22 is supported by a stage surface
plate 24 supported by the floor or base, and supports

- 34 -

and aligns a wafer. The reticle stage 21 is supported by
the reticle stage surface plate 20 supported by the lens
barrel surface plate 17 , and movably supports a reticle
bearing a circuit pattern. The bar mirror of the first
5 embodiment is integrated with the lens barrel surface
plate 17. An illumination optical system 25 generates
exposure light for exposing the wafer on the wafer stage
22 to the reticle set on the reticle stage 21.

The wafer stage 22 is scanned in synchronism with

10 the reticle stage 21. During scan of the reticle and

wafer stages 21 and 22, their positions are continuously
detected by corresponding interferometers and fed back
to the driving units of the reticle and wafer stages 21
and 22. This enables accurately synchronizing the scan

15 start positions of the reticle and wafer stages 21 and
22 and controlling the scan speed in a constant-speed
scan region at high precision. While the reticle and
wafer stages 21 and 22 are scanned with respect to the
projection optical system 23, the wafer is exposed to

20 the reticle pattern, and the circuit pattern is
transferred.

The fourth embodiment adopts the
interferometer-mounted stage apparatus of the first
embodiment as a reticle stage. Thus, the stage position

25 can be measured by using the projection optical system
as a reference, and high-speed, high-precision exposure
can be realized.

- 35 -

<Embodiment of Semiconductor Production System>

A production system for a semiconductor device
(semiconductor chip such as an IC or LSI, liquid crystal
panel, CCD, thin-film magnetic head, microma chine, or
5 the like) will be exemplified. A trouble remedy or
periodic maintenance of a manufacturing apparatus
installed in a semiconductor manufacturing factory, or
maintenance service such as software distribution is
performed by using, e.g., a computer network outside the

10 manufacturing factory.

Fig. 7 shows the overall system cut out at a given
angle. In Fig. 7, reference numeral 101 denotes a
business office of a vendor (apparatus supply
manufacturer) which provides a semiconductor device

15 manufacturing apparatus. Assumed examples of the

manufacturing apparatus are semiconductor manufacturing
apparatuses for various processes used in a
semiconductor manufacturing factory, such as pre-process
apparatuses (lithography apparatus including an exposure

20 apparatus, resist processing apparatus, and etching

apparatus, annealing apparatus, film formation apparatus,
planarization apparatus, and the like) and post-process
apparatuses (assembly apparatus, inspection apparatus,
and the like) . The business office 101 comprises a host

25 management system 108 for providing a maintenance

database for the manufacturing apparatus, a plurality of
operation terminal computers 110, and a LAN (Local Area

- 36 -

Network) 109 which connects the host management system
108 and computers 110 to build an intranet. The host
management system 108 has a gateway for connecting the
LAN 109 to Internet 105 as an external network of the
5 business office, and a security function for limiting
external accesses .

Reference numerals 102 to 104 denote manufacturing
factories of the semiconductor manufacturer as users of
manufacturing apparatuses. The manufacturing factories

10 102 to 104 may belong to different manufacturers or the
same manufacturer (pre-process factory, post-process
factory, and the like) . Each of the factories 102 to 104
is equipped with a plurality of manufacturing
apparatuses 106, a LAN (Local Area Network) 111 which

15 connects these apparatuses 106 to construct an intranet,
and a host management system 107 serving as a monitoring
apparatus for monitoring the operation status of each
manufacturing apparatus 106. The host management system
107 in each of the factories 102 to 104 has a gateway

20 for connecting the LAN 111 in the factory to the

Internet 105 as an external network of the factory. Each
factory can access the host management system 108 of the
vendor 101 from the LAN 111 via the Internet 105. The
security function of the host management system 108

25 authorizes access of only a limited user. More

specifically/ the factory notifies the vendor via the
Internet 105 of status information (e.g., the symptom of

- 37 -

a manufacturing apparatus in trouble) representing the
operation status of each manufacturing apparatus 106,
and receives response information (e.g., information
designating a remedy against the trouble, or remedy
software or data) corresponding to the notification, or
maintenance information such as the latest software or
help information. Data communication between the
factories 102 to 104 and the vendor 101 and data
communication via the LAN 111 in each factory adopt a
communication protocol (TCP/IP) generally used in the
Internet. Instead of using the Internet as an external
network of the factory, a dedicated network (e.g., ISDN)
having high security which inhibits access of a third
party can be adopted. Also the user may construct a
database in addition to the one provided by the vendor
and set the database on an external network, and the
host management system may authorize access to the
database from a plurality of user factories.

Fig. 8 is a view showing the concept of the
overall system of this embodiment that is cut out at a
different angle from Fig. 7. In the above example, a
plurality of user factories having manufacturing
apparatuses and the management system of the
manufacturing apparatus vendor are connected via an
external network, and production management of each
factory or information of at least one manufacturing
apparatus is communicated via the external network. In

- 38 -

the example of Fig. 8, a factory having manufacturing
apparatuses of a plurality of vendors and the management
systems of the vendors for these manufacturing
apparatuses are connected via the external network of
5 the factory, and maintenance information of each

manufacturing apparatus is communicated. In Fig. 8,
reference numeral 201 denotes a manufacturing factory of
a manufacturing apparatus user (semiconductor device
■iJ3 manufacturer) where manufacturing apparatuses for

y! 10 various processes, e.g., an exposure apparatus 202,
01 resist processing apparatus 203, and film formation

apparatus 204 are installed in the manufacturing line of
r-l the factory. Fig. 8 shows only one manufacturing factory

201, but a plurality of factories are networked in
S 15 practice. The respective apparatuses in the factory are
connected to a LAN 2060 to build an intranet, and a host
management system 205 manages the operation of the
manufacturing line. The business offices of vendors
(apparatus supply manufacturers) such as an exposure
20 apparatus manufacturer 210, resist processing apparatus
manufacturer 220, and film formation apparatus
manufacturer 230 comprise host management systems 211,
221, and 231 for executing remote maintenance for the
supplied apparatuses. Each host management system has a
25 maintenance database and a gateway for an external

network, as described above. The host management system
205 for managing the apparatuses in the manufacturing

- 39 -

factory of the user, and the management systems 211, 221,
and 231 of the vendors for the respective apparatuses
are connected via the Internet or dedicated network
serving as an external network 200. If a trouble occurs
5 in any one of a series of manufacturing apparatuses
along the manufacturing line in this system, the
operation of the manufacturing line stops. This trouble
can be quickly solved by remote maintenance from the
vendor of the apparatus in trouble via the Internet 200.

10 This can minimize the stop of the manufacturing line.

Each manufacturing apparatus in the semiconductor
manufacturing factory comprises a display, a network
interface, and a computer for executing network access
software and apparatus operating software which are

15 stored in a storage device. The storage device is a

built-in memory, hard disk, or network file server. The
network access software includes a dedicated or
general-purpose web browser, and provides a user
interface having a window as shown in Fig. 9 on the

20 display. While referring to this window, the operator
who manages manufacturing apparatuses in each factory
inputs, in input items on the windows, pieces of
information such as the type of manufacturing apparatus
(401), serial number (402), subject of trouble (403),

25 occurrence date (404), degree of urgency (405), symptom
(406), remedy (407), and progress (408). The pieces of
input information are transmitted to the maintenance

- 40 -

database via the Internet, and appropriate maintenance
information is sent back from the maintenance database
and displayed on the display. The user interface
provided by the web browser realizes hyperlink functions
5 {410 to 412), as shown in Fig. 9. This allows the

operator to access detailed information of each item,
receive the latest-version software to be used for a
manufacturing apparatus from a software library provided
by a vendor, and receive an operation guide (help

10 information) as a reference for the operator in the
factory. Maintenance information provided by the
maintenance database also includes information
concerning the features of the present invention
described above. The software library also provides the

15 latest software for implementing the features of the
present invention.

A semiconductor device manufacturing process using
the above-described production system will be explained.
Fig. 10 shows the flow of the whole manufacturing

20 process of the semiconductor device. In step 1 (circuit
design), a semiconductor device circuit is designed. In
step 2 (mask formation) , a mask having the designed
circuit pattern is formed. In step 3 (wafer manufacture) ,
a wafer is manufactured by using a material such as

25 silicon. In step 4 (wafer process) called a pre-process,
an actual circuit is formed on the wafer by lithography
using a prepared mask and the wafer. Step 5 (assembly)

- 41 -

called a post-process Is the step of forming a
semiconductor chip by using the wafer manufactured in
step 4, and includes an assembly process (dicing and
bonding) and packaging process (chip encapsulation) . In
5 step 6 (inspection) , inspections such as the operation
confirmation test and durability test of the
semiconductor device manufactured in step 5 are
conducted. After these steps, the semiconductor device
is completed and shipped (step 7) . For example , the

10 pre-process and post-process are performed in separate

dedicated factories, and maintenance is done for each of
the factories by the above-described remote maintenance
system. Information for production management and
apparatus maintenance is communicated between the

15 pre-process factory and the post-process factory via the
Internet or dedicated network.

Fig. 11 shows the detailed flow of the wafer
process. In step 11 (oxidation), the wafer surface is
oxidized. In step 12 (CVD) , an insulating film is formed

20 on the wafer surface. In step 13 (electrode formation),
an electrode is formed on the wafer by vapor deposition.
In step 14 (ion implantation) , ions are implanted in the
wafer. In step 15 (resist processing) , a photosensitive
agent is applied to the wafer. In step 16 (exposure),

25 the above-mentioned exposure apparatus exposes the wafer
to the circuit pattern of a mask. In step 17
(developing) , the exposed wafer is developed. In step 18

- 42 -

(etching) , the resist is etched except for the developed
resist image. In step 19 (resist removal), an
unnecessary resist after etching is removed. These steps
are repeated to form multiple circuit patterns on the
5 wafer. A manufacturing apparatus used in each step

undergoes maintenance by the remote maintenance system,
which prevents a trouble in advance. Even if a trouble
occurs, the manufacturing apparatus can be quickly
recovered. The productivity of the semiconductor device

10 can be increased in comparison with the prior art.

The present invention is not limited to the above
embodiments and various changes and modifications can be
made within the spirit and scope of the present
invention. Therefore, to apprise the public of the scope

15 of the present invention the following claims are made.

- 43 -